As a stage and screen musical, Victor Hugo’s French-revolutionary epic took on a whole new life, so it’s a bold move for the BBC to reboot the beloved ‘Les Mis’ as a costume drama. Kudos, then, to this incarnation from master adapter Andrew Davies and a cast including Dominic West, Olivia Colman and David Oyelowo: unless you really love those tunes, this six-parter knocks the singing-and-dancing one into a cocked tricorne.

For producer Chris Carey, whose past credits range from dramas Apple Tree Yard and River to Mitchell and Webb comedy The Ambassadors, the secret was an under-appreciated corner of northern France. To create their early-19th-century France, he and his team looked at usual suspects Prague and Budapest. ‘They both do Paris very well,’ says Carey, ‘but for the variety of locations that Les Misérables has we just felt Belgium and northern France, the French Ardennes and then into the Belgian Ardennes, were the most authentic we could get.’

For the series’ opening scene, a panorama of the killing fields of Waterloo, this meant the authenticity was particularly high. ‘That was filmed about 15 miles from the battle, about 40 miles south of Brussels,’ he says. ‘We just found a field with a ditch and a friendly farmer and carved it up, then added 20,000 men and 500 dead horses with the help of a bit of computer-generated stuff.’

Scenes in the southern town of Toulon, where we first meet Valjean (West) suffering in the prison gangs, were recreated in Sedan (pictured above), on the French side – besides Brussels, the series’ most-used location. Though the interiors were shot in a studio, we see the prisoners emerging from the city’s Château Fort, one of the largest medieval forts in Europe (now a hotel), and the quarry where they labour is about five miles outside the town.

On his release, Valjean is taken in by the bishop in the hill town of Digne, which was filmed in Marville (pictured above), 35 miles south-east of Sedan. This is a miraculously preserved village ­– ‘It’s Lark Rise to Candleford in France,’ says Carey. ‘The fountain Valjean drinks from and the church in the square, even the bishop’s garden were real. All we did was put a bit of stuff down on the ground and remove some aerials in post-production.’

Valjean’s next port of call comes in Episode 2, with Montreuil-sur-Mer. This was filmed in Limbourg (pictured above), on the eastern borders of Belgium. ‘Again, it looks exactly as it does on the tin,’ says Carey. ‘It’s great because, even though it’s not far away, it’s got a very different feel from the summery heat of Digne – we filmed in the winter, so it’s cold and greys and blues.’

Episode 3 sees another key location, the inn run by the Thénardiers (Olivia Colman and Adeel Akhtar). For this, the exterior was shot at the Château de Meez, a riding school near Yvoir, about 50 miles from Brussels, and the interiors were in the Château d’Ecaussines-Lalaing (pictured above), a grand rococo castle nearby. While this venue provided the perfect period bar area – ‘We literally walked into the room and said, “That’s great,”’ – it also gave them a space that, with some redressing, doubled as the courtroom seen at the start of the same episode.

Of course, the real star of Les Misérables is Paris, a presence from the first episode. ‘Ours is actually an amalgam of a variety of places,’ says Carey. ‘There’s Brussels, a bit of Ghent (pictured above), a lot of Sedan, a bit of Huis in Belgium, the river in Namur. We went everywhere and pieced it all together with a bit of help from CGI.’

In Brussels, the house of Gillenormand (David Bradley) and Marius (Josh O’Connor) was filmed inside antique shop Costermans on Place du Grand Sablon. For the exteriors, they moved to Rue du Peuplier near Sainte Cathérine, with the church of St Sulpice played by St Jean Baptiste au Béguinage, a 17th-century Flemish baroque construction.

Brussels is also where we see Fontine (Lily Collins) on a romantic boating trip with her beau Felix (Johnny Flynn), or at least the village of La Hulpe just to the south, where the 19th-century neo-Renaissance château (pictured above) also provided the venue for their lunch. Ghent, to the north-west, was used for a busy street scene. ‘We turned a riverside there into a Parisian marketplace and dropped Notre Dame into the background with CG – no spire, because it was built without it,’ explains Carey. ‘We really wanted Paris to feel wide and open and epic, so we’d take over bridges or quaysides, where 100 feet around the camera would have the same essential architecture, and then fill in at the back with CGI.’

For the climax of the series, at the revolutionary barricades, they were back in Sedan. ‘That was in a real street, in the middle of the night, and they let us blow it up,’ says Carey, still not quite believing it. ‘It took a phenomenal amount of arrangement – and great patience on their part not to lose faith at two in the morning when we’re firing guns and shooting cannons and the locals are complaining.’

Tempers were assuaged by extra business at the pizza takeaway – ‘I think they did very well out of the 150 extra people in town’ – but Carey’s also returning in January to give the citoyens a special screening. He’s also spreading the word about his discovery: ‘It’s an amazing town, and a really beautiful and interesting region,’ he says. ‘That whole area of northern France is so gorgeous and visitors just don’t go there enough.’